Conventional window coverings which use a series of horizontally disposed, vertically arranged slats are available in a variety of styles. The typical structure for supporting the slats vertically spaced from each other includes an end ladder arrangement having a series of cross connectors upon which the slats rest. In the 1950's the ladder arrangement included a wide tape and the cross connectors included a series of generally horizontal tape sections joining the a front and rear vertical ladder tape. Movement of the front vertical ladder tape with respect to the rear vertical ladder tape caused a tilting of the horizontal tape section and consequent tilting of the supported louver or slat resting on the horizontal tape section.
The initial use of a soft vertical ladder tape enabled the lowest base louver or slat to be raised while sequentially collecting slats against the rising lowest base louver while enabling collapse of each vertical ladder tape section between adjacent horizontal tape sections as slats were collected together against the base slat. As the base slat was raised to its uppermost position, the slats would be collected into a closely adjacent group nearest an upper head rail which typically provided fittings for operating the window covering blinds set. Control of the operation of the window covering blinds set typically involved a lift cord for raising the base slat and collecting the slats in a group just underneath the head rail to place the window covering blinds set in a lifted, open position, and a tilt control used to raise or lower the front vertical ladder tape with respect to the rear vertical ladder tape to cause a tilting of the horizontal tape section to control the angle of tilt of the supported louvers resting on the horizontal tape sections.
Traditionally, two collections of cords were used to enable control of the lift control for opening the window covering blinds set and the tilt control, respectively. Tilt control was typically achieved by pulling one side of a looped cord to cause the front vertical ladder tape with respect to the rear vertical ladder tape with direct visual feedback. The lift control was achieved typically by pulling a pair of joined or length coordinated cords from one side of the head rail so that each side of base slat would be lifted evenly. Without length coordination of the lift cords, one side of the base slat would begin to raise higher than the other. Often the coordination was done with a metal slip buckle.
In the early days, the pair of cords which raised and lowered the blinds were a loop at the bottom, with the loop being lowered as the window covering set was raised, and raised as the window covering set was lowered. Children were known to play with the end of the lift cord, and the lower end of the lift cord was even more available when the window covering set was raised. Children were also known to accidentally become caught in the lower loop. In some cases choking can occur.
Other structures were recently employed to keep lift cords joined, including placing the coordination between the cords high and near the head rail. The head rail is a metal structure which may be high up and near a metal rail which provides support for the window covering as well as actuation hardware. This arrangement works less well with vertically tall window covering sets because the raising of the slat set puts even more loose cord at or near the ground. Further, where the window covering set was particularly vertically high, the user might find the uppermost starting position of the coordinated cords to be inaccessible.
In another configuration, the lift cords were separated into individual cord members and secured within a cord safety connector which is used to both tension, secure, collect and enable tension pulling and actuation either by grasping the safety connector or optionally by grasping a single cord which extends from the bottom of the safety connector. A safety connector acts to keep the cords coordinated if operated by direct manual grasping and actuation of the safety connector, or by a cord extending below it, but will break apart if an object enters between two cords and bears down upon the safety connector. Safety connectors which completely separate and leave only single dangling cords which are generally incapable of causing a choking or strangling hazard.
In the earliest window coverings, the control of the tilt of the louvers or slats was accomplished by using a pair of opposed cords. Unlike the lift cords which were better to be coordinated, the tilt cords were intended to work oppositely. When one cord is pulled, the other cord retracts, and vice versa. In some of the earlier window coverings an operable loop was possible, but it was generally preferred to have a pair of cords, each having its own terminus, especially also to distinguish it from the coordinated lift cord. The tilt mechanism basically consisted of the turning of a drum over one ladder tape set and which may have a shaft to transmit turning to a second and or subsequent ladder sets.
In view of the foregoing, the area inside the head rail had two sets of distributive controls. Taken from the upper front of a head rail and looking to the right, a double or triple or quadruple coordinated cord set would enter into the head rail and each would be distributed to locations directly over the ladder tape or ladder cord, extend through apertures in the head rail and then typically through individual slat apertures in the lateral centers of the slats and finally to some fixed position on the bottom slat. As the lift cords were taken in toward the head rail, the bottom fixed slat would rise to collect the other slats near the underside of the head rail.
Some window coverings have “rootless” or “no-holes” slat sets which either route the lift cord through some structure located to a rear side of the slat, or which may use a pair of guided lift cords which are held relatively closely to the ladder cord matrix. The so-called “routless” feature was developed primarily to eliminate the aperture from the center of the slats. In other slat sets, a center aperture is set to be of a diameter for fitting closely around a lift cord. Window covering sets which are “routless” generally still typically use a lift cord set which can come into contact near the floor and create a danger for children and pets.
At the other end of the head rail, the pair of tilt cords would operate a drum to cause the raising or lowering of the front vertical ladder tape or member with respect to the rear vertical ladder tape or member to cause a tilting of the horizontal tape section to control the angle of tilt of the supported slats resting on the horizontal tape or horizontal ladder cord sections. In later models of the window coverings, a wand was provided with a reduction gear so that a user could easily manipulate the wand by turning it with fingers to cause the raising or lowering of the front vertical ladder member with respect to the rear vertical ladder member to cause tilting of the horizontal ladder section to control the angle of tilt of the supported slats as previously described. However there has been no effective substitute for the operation of the lift cord sets.
In the traditional slat window covering, tilt was able to occur independently of lift. Although with some friction, the slats could be lifted while they were in a forward, rearward or neutral tilt angle. Likewise, a tilt adjustment could occur regardless of whether the slat set was fully extended or closed, whether it was half way open, or whether it was at the full open position. Exact simultaneous activation is not an overriding advantage, but the main objective is safety and elimination of the lift cord set has been viewed as the major objective in making window covering slats safer.
Even in conventional manually operated window covering sets, the concern over safety is so high that even those structures with hanging slat lift cords often have stops mounted on the manually operable lift cords near the points of entry into the head rail and that will prevent children and pets from “fishing out” any appreciable extra length of lift slat cord from in between any two adjacent slats, as such pick might form a potentially dangerous loop. Slat angle adjustment cords have separate ends an are typically short and located near the top of the window covering blind set which makes it a solution which is limited by the height of the blind set. Elimination of the ability to tamper with the window covering blind set so as to form a dangerous loop is a high priority.
What is needed is a window covering slat set which can be manually or electrically actuated and having a control input which eliminates as much as possible any potential for unwanted, dangerous entanglement with humans. The needed solution should eliminate all dangling control cords extending from the head rail. The needed solution should permit a slat-type window covering to be opened and closed and have the angle of tilt of the slats adjusted regardless of the degree to which the slat set is raised.